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Electronics Forum / Basics / April 2007Soldering tiny (e.g. PLCC, LFCSP, CLCC) ICs
What do hobbyists do if the IC they want is only available in a tiny 5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an accelerometer made by Analog Devices.) Are there snap-in adapters out there that would give me a more PDIP-like pin-out? I have seen suggestions, on sci.electronics.design, for how to solder the tiny buggers, but the implied soldering skill level seems way beyond me (and besides, at $20 per accelerometer IC, I'm not eager to do too much learning-by-doing here!) > What do hobbyists do if the IC they want is only available in a tiny > 5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an [quoted text clipped - 4 lines] > (and besides, at $20 per accelerometer IC, I'm not eager to do too > much learning-by-doing here!) How sensitive is it to heat? > > What do hobbyists do if the IC they want is only available in a tiny > > 5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an [quoted text clipped - 6 lines] > > How sensitive is it to heat? The data sheet says storage temperature is -65C to +150C. But they also give detailed soldering-related information, which I've grabbed and posted at the following location if you care to look at it: http://trhj.homeunix.net/~strnbrg/soldering.jpg. >> > What do hobbyists do if the IC they want is only available in a tiny >> > 5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an [quoted text clipped - 11 lines] > and posted at the following location if you care to look at it: > http://trhj.homeunix.net/~strnbrg/soldering.jpg. The important point is whether its any more sensitive to heat than a non specialised common IC types. If heat is not particularly an issue there is a technique that can be applied to SMD chips with close pin spacings. Tac the corner pins to the pads as accurately as you can then flow solder along the row of pins with the tip of the iron, next hold the board upside down overhead and re-melt the solder - do this over the waste paper basket as the solder drops are evil to get out of carpet! This was always easy with lead/tin solder but is likely to be much more difficult with lead-free, plenty of flux is the only solution. Once you have removed the bulk of the solder let the chip cool (have a cuppa) then you can deal with the solder bridges between pins, again with plenty of flux tease the bridges away from the chip body with the board upside down & overhead - tilt it slightly so gravity helps the solder to go the way you want. If you want fine pitch SMD chips to practice on - a scrap VCR or cable box might be a good place to look. >>> > What do hobbyists do if the IC they want is only available in a tiny >>> > 5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an [quoted text clipped - 33 lines] > If you want fine pitch SMD chips to practice on - a scrap VCR or cable box > might be a good place to look. How bout pre-solder the ic and pads? Should make it easier? If you could heat up some solder you could dip the ic into the solder and do it pretty quickly(not all the way of course). Although I'm not sure if its worth that unless you plan on doing many of them. The way I saw to do this was use wick to soak up the solder. >>>> > What do hobbyists do if the IC they want is only available in a tiny >>>> > 5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an [quoted text clipped - 41 lines] > > The way I saw to do this was use wick to soak up the solder. Pre-soldering is a very bad idea - its impossible to get even thickness on each pad & each pin, this also makes it difficult to accurately line up the pins and the chip mounting looks uneven & scruffy. The process of flowing the pins uses too much solder to suck up with wick (unless you don't mind using a whole reel on one chip) and there's a risk of the solder cooling either side of the point the iron is applied - you have to be very careful not to pull up or bend the pins as you separate the wick away. >>>>> > What do hobbyists do if the IC they want is only available in a tiny >>>>> > 5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an [quoted text clipped - 51 lines] > have to be very careful not to pull up or bend the pins as you separate > the wick away. The video's I saw of the guy doing this was pretty good. He didn't seem to have any of these issues(or atleast they were easily fixed). I thought I had the link to it but I guess not. I think some of them are on youtube too. > What do hobbyists do if the IC they want is only available in a tiny > 5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an [quoted text clipped - 4 lines] > (and besides, at $20 per accelerometer IC, I'm not eager to do too > much learning-by-doing here!) I've seen soic done with a heat gun and a soldering iron using solder wick. I've also seen those who have build there own ovens. Maybe your best bet is to get a few cheap components that have similar packages and practice on them? You might discover an easy way to do it. >What do hobbyists do if the IC they want is only available in a tiny >5mm-on-a-side format, like CLCC? (I'm thinking, specifically, of an [quoted text clipped - 4 lines] >(and besides, at $20 per accelerometer IC, I'm not eager to do too >much learning-by-doing here!) Thry this link: http://www.schmartboard.com/ Looks like maybe just what you need. ERS I haven't done leadless chips yet (although I've done a leadless SMT socket once), but I've been able to solder pretty much everything else, down to 0.4mm pitch and 01005 caps. For the really fine stuff, what I usually do is put down solder paste (with a brass home-etched stencil, perhaps), and either heat it from beneath the PCB with a hotplate (or electric frying pan), or for 01005's and other two-pins, use a soldering iron to melt the paste without needing to touch the actual part - just touch the copper trace next to the paste and let the heat reflow the paste. I find that not touching the part itself with the iron keeps it from moving around. I did SOJ with the hotplate, with zero fauls on eight SRAM chips, and that was without a stencil. Related pages: http://www.delorie.com/pcb/brass/ - home-etched brass paste stencils http://www.delorie.com/pcb/hotplate/ - the hotplate I use http://www.delorie.com/pcb/smd-challenge/ - 01005 and 0.4mm parts http://www.delorie.com/house/furnace/pcb2/ - tssop and the one SMT socket http://www.delorie.com/pcb/m3a/ - the SOJ sram chips http://www.stencilsunlimited.com/solder_products.php - the paste I use |
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